Field
This invention relates generally to a deformable permanent fastener and, more particularly, to a permanent fastener for joining two work pieces, where the fastener includes a headed pin passing through holes in the work pieces with locking grooves on a shank portion, and a retaining collar composed of an amorphous metal alloy, where the collar is heated into a thermoplastic region and radially compressed such that the collar deforms to engage with the locking grooves on the shank portion of the pin.
Discussion
Various industries, including aviation, general construction, electronics, and general manufacturing, use fasteners for a number of different purposes. For example, in the aviation industry, aircraft structures are often comprised of two or more panels—which may be made of the same material or different materials, and which must be permanently fastened together.
Many different types of fasteners for joining two work pieces have been developed over the years—including everything from old-fashioned pounded rivets, to fasteners made of modern materials. Traditional one-piece or two-piece fasteners requiring plastic deformation upon installation have been used in various applications. However, in the aircraft industry, these fasteners require multiple production steps to ensure proper grain boundary control in the metal, and multiple installation and post-processing steps such as machining and inspection. These procedural steps add time and cost to the usage of plastically deformed metal fasteners. In addition, these fasteners use materials with grain boundaries which are inherently susceptible to onset and propagation of corrosion, stress concentrations and fatigue.
Threaded fasteners do not involve plastic deformation upon installation, but typically employ materials with the same limitations and susceptibilities as described above for plastically deformed metal fasteners. In addition, threaded fasteners are prone to inconsistent clamp-up force, and are also vulnerable to creep or loosening due to vibrations and shock experienced during service life.
In a highly fatigue-sensitive environment such as an aircraft structure, a fastener is needed which offers reduced installation time and fewer installation steps than traditional plastically-formed fasteners, better fastener material properties, more fastener geometric options, improved fastener gripping strength, more consistent clamping force, and resistance to vibration and shock. These features can be achieved with the amorphous metal fastener designs disclosed herein.